This invention relates to an earth boring bit for boring very precise circular holes in the earth. Such holes include, but are not limited to, holes for foundation piers, footings and the like. Prior art auger-type machines are typically used to drill holes in the earth, and present a number of disadvantages. Specifically, the auger transports the earth upwardly and spills it on the ground around the hole. In many instances, the earth around the hole may fall back into the hole when the auger is removed, or may fall into nearby footings or foundation piers. In addition, boring a hole to a precise depth with an auger is difficult, since the auger provides no visual cues as to the distance of the tip of the auger below the earth. The flights of the auger must be relatively far apart to accommodate the earth being removed from the hole. This reduces the precision with which the hole is bored, and increases the amount of earth which falls from the auger when the auger is removed from the hole. Finally, even if the earth removed from the hole by the auger does not fall back into the hole, the earth is piled around the hole and must be removed by a completely separate operation, generally by hand by a laborer who uses a shovel.
The invention of the present application addresses the problems presented by prior art augers by providing a unique, rotating earth boring bit. The earth boring bit includes a cylindrical drum having an open lower end to which a plate is attached. Unique cutting assemblies are positioned on the plate. The earth boring bit is operatively connected to a hydraulic motor on a mobile machine such as a skid steer backhoe. Powered by the hydraulic motor of the mobile machine, the earth boring bit rotates, thereby causing the cutting assemblies to bore a hole into the earth by slicing and upturning the earth, and directing the upturned earth into the drum. The upturned earth is maintained within the drum until the boring process is completed, and is then removed from the drum after the earth boring bit has been moved to a location away from the freshly-bored hole. The unique structure of the present invention thus overcomes the disadvantages of prior art augers by providing an earth boring bit which is capable of boring a hole which has sidewalls that are perpendicular to the bottom of the hole, and which is free of upturned earth. The holes bored by the earth boring bit of the present invention are so precise that multiple holes may be bored in close proximity to one another without jeopardizing the structure of a single hole.
Therefore, it is an object of the invention to provide an earth boring bit which bores a hole of a precise depth and in a precise location.
It is another object of the invention to provide an earth boring bit that does not spill the earth from the bored hole onto the ground around and near the hole as the hole is being bored.
It is yet another object of the invention to provide an earth boring bit which includes means for transporting the earth removed from the bored hole to a predetermined location away from the hole for disposal.
It is another object of the invention to provide an earth boring bit which forms a clean, uniformly-sized hole having a relatively flat bottom and relatively perpendicular sides.
It is another object of the invention to provide an earth boring bit which can be operated from a tractor, backhoe, or other mobile machines.
These and other embodiments of the invention are achieved in the preferred embodiments disclosed below by providing an earth boring bit for boring a hole having a predetermined depth into the earth. The earth boring bit includes a cylindrical drum for being mounted for rotation on the end of a boom of a mobile machine and connected to and rotated by a power supply mounted on the boom. The drum includes an exterior for defining the diameter of the hole being bored and an interior adapted for receiving upturned earth therein as the hole is being bored. A plate is mounted in the drum adjacent a lower end thereof for movement between a closed position for cooperating with the interior of the drum for retaining the upturned earth therein and an open position for dispensing the upturned earth out of the interior of the drum at a predetermined location away from the hole being bored. At least one cutting member is carried on the plate for cutting the earth in a thin, progressive slice and directing the earth into the drum, thereby boring the hole into the earth.
According to one preferred embodiment of the invention, the cutting member includes an opening extending through the plate and defined by adjacent teeth projecting outwardly away from the plate for cutting the earth into the progressive slice as the boring assembly rotates.
According to another preferred embodiment of the invention, the earth boring bit includes a pilot bit centrally positioned on and extending outwardly away from the plate for making a pilot hole in the earth for centering the earth boring bit within the hole as the earth boring bit rotates.
According to yet another preferred embodiment of the invention, the earth boring bit includes a spring-loaded handle engaging the plate for moving the plate between said open and closed positions.
According to yet another preferred embodiment of the invention, the handle includes an elongate rod having first and second ends. The rod is positioned within and extends through the interior of the drum. A latch is connected to the second end and cooperates with a complementary keyhole defined in and extending through the plate. The latch has a longitudinal axis positioned perpendicular to the longitudinal axis of the keyhole for maintaining the plate in its closed position. The latch is positioned parallel to the longitudinal axis of the keyhole for moving the plate into the open position. A handle is connected to the first end of the rod and cooperates therewith for selectively moving the latch between the perpendicular and parallel positions, thereby moving the plate between the closed and open positions, respectively.
According to yet another preferred embodiment of the invention, the earth boring bit includes two cutting members positioned in radial opposition to one another. The teeth on each of the cutting members collectively define a cutting edge extending perpendicularly from the pilot bit, thereby creating a cutting edge having an effective diameter equal to the diameter of the drum.
According to yet another preferred embodiment of the invention, the earth boring bit includes two opposing interior cutting members and two opposing exterior cutting members.
According to yet another preferred embodiment of the invention, each of the interior cutting members is positioned adjacent to the pilot bit, and each of the exterior cutting members is positioned adjacent to an outer edge of the plate.
According to yet another preferred embodiment of the invention, the teeth on each of the exterior cutting members form a cutting edge extending beyond said outer edge of the plate and having an effective diameter extending beyond the diameter of the plate for reducing friction on the exterior of the drum as the earth boring bit rotates.
According to yet another preferred embodiment of the invention, the teeth on each of the interior and exterior cutting members collectively define a cutting edge extending perpendicularly from the pilot bit for cutting a progressive slice of earth having a diameter which extends across the diameter of the plate.
According to yet another preferred embodiment of the invention, the plate and drum are pivotally connected together along common joint edges by a hinge element for permitting the plate to move between the open and closed positions.
According to yet another preferred embodiment of the invention, the earth boring bit includes a drive shaft operatively connected to the power supply mounted on the boom, wherein the drum and plate are coaxially mounted on said drive shaft for rotation therewith.